Analyses of distribution, diversity, endemism, and taxonomic effort for Rubiaceae are reported, based on queries from a World Rubiaceae Checklist database. Rubiaceae are widespread and occur in all major regions of the world except the Antarctic Continent, but are predominantly a group in the tropics with greatest diversity in low- to mid-altitude humid forests. A count of Rubiaceae species and genera is given (13,143 spp./611 genera), which confirms that this is the fourth largest angiosperm family. Psychotria L. is the largest genus in the Rubiaceae (1834 spp.) and the third largest angiosperm genus. Most genera (72%) have fewer than 10 species and 211 are monotypic. Calculation of relative species diversity and percentage endemism enables areas of high diversity and endemism to be enumerated, and identifies areas where further field collecting and taxonomic research are required. Endemism is generally high in Rubiaceae, which supports data from recent studies showing that many species have restricted distributions. Given the assumed ecologic sensitivity of Rubiaceae, in combination with a range of other factors including restricted distribution, we suggest that species in this family are particularly vulnerable to extinction. The rate at which new species are being described is inadequate; more resources are required before the diversity of Rubiaceae is satisfactorily enumerated.